JP2513442C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reading a coded code such as a bar code. The term "coded code" is inclusive and includes all of codes, marks and patterns. The invention is particularly suitable for hand-held bar code scanning devices. [0002] The so-called barcodes commonly used today consist of a collection of parallel bar-like shapes of different widths shaped in a rectangle. This includes the use of Unified Product Code (UPC) specifications or other barcodes such as Code 39, Interleaved Two of Five, and Codabar. [0003] A typical bar code scanner currently in use generates a laser beam using a gas racer such as a He-Ne laser. The beam is easily visible even in a brightly lit environment, so that the illuminated barcode is visible. However, smaller laser generators have been desired to reduce the size of bar code scanners, and laser diodes have been used. The laser diode is typically a gallium arsenide (typically gallium aluminum arsenide GaAlAs) laser material that generates laser light in the infrared region (815 nm level wavelength). Since the diameter of the laser beam is very small, it is not always easy to irradiate the bar code without removing it, which hinders use and hinders its spread. The problem is solved by using an invisible light beam and simultaneously irradiating a coaxial tracking beam of visible light to enable a failure-free scan. This is a problem of the original application of the present application (Japanese Patent Application No. 59-172521). Another problem with the hand-held coded code detection device is that the coded code (
Clear reading may not be possible unless the scanning device is placed at a certain distance from the product (usually on the product label). This is because the illuminance on the photodetector in response to the reflected light, and hence the output signal from the photodetector, varies with the distance between the coded code and the scanning device. It is a feature of the present invention to provide a hand-held coded code detection optical device that minimizes fluctuations in the output from the detector by condensing light so as to give a constant illuminance to the detector. This problem is a problem of another divisional application (Japanese Patent Application No. 5-213797) of the present application of the present application. [0005] The potential of affordable bar code scanners depends on how the optical and electro-optical components are integrated. These components must be packaged so that they are easy to assemble in a housing that is small enough to be grasped, as well as the shock and vibration generated by the optics during assembly and use of the scanning device. Must be protected against. This is the subject of the present invention.
The purpose of the invention is to solve this problem. A feature of the present invention is that the laser-operating electronic components are simply mounted on a printed circuit board that forms the base that supports the optical components as well as the laser and other electronic components of the scanning device, such as a photodetector. It is provided as one assembly. According to the present invention, there is provided a housing having a port, and a light beam for irradiating a coded code including a relatively large reflection area and a small reflection area is emitted from the housing through the port. is, the port light rays reflected from the coded code
, A laser diode and an optical system for forming the light beam, a photodetector for receiving the reflected light beam, and means for supporting the photodetector in the housing. And a printed circuit board having a circuit for connecting to the diode and the photodetector, wherein the laser diode and the optical system are assembled in a housing in a relation supported on the printed circuit board to form a single structure. A code or code detecting device comprising the relatively large reflection area and the relatively small reflection area is provided. Preferably, said assembling means also assembles said optics with said laser diode, said photodetector and said printed circuit board in said single structure. DETAILED DESCRIPTION OF THE INVENTION The purpose and configuration of the present invention are as described above ([0005] and [00061] , but the embodiments described below are based on the special circumstances that the present application is a divisional application. In order to solve the problems described at the beginning of the above-mentioned section of the prior art, a description will be given of a mode including a combination of invisible light and visible light. A barcode scanning gun 10, which is one embodiment of a scanning gun or simply a gun), is shown having a housing 12 comprising an upper portion 14 and a handle portion 16. The housing is preferably injection molded of plastic. The housing is divided into right and left halves, which are initially open to accommodate the optical, electro-optical and electronics assembly 20 of the scanning device. Is. Display board 22, a display lamp 24
A port 26 is provided at the rear end for an audible tone generated to indicate that the scan was successful, but this is not required. The display may be a liquid crystal display or a light emitting diode, and is appropriately adopted. The light emitting diode indicates the scanning state of the scanning device (whether the scanning device is on, off, or inactive);
It can also indicate when the scan was successful. The front end 28 of the upper portion 14 of the housing 12 has an opening through which the scanning beam and the reflected light from the bar code pass. This aperture is called a beam port 30, and a condenser lens 32 is attached to the housing shoulders 36 and 38 in the beam port 28. The scanning device is small for convenience in handling. Suitably, front end 2
The horizontal length between the upper housing 8 and the rear end 18 is about 5 inches (12.5 cm), the top of the upper housing is about 5.5 inches (13.8 cm), and the width between the upper housings 14. Is about 1.75 inches (4.38 cm). The coded code is located at a distance of about 10 inches (25 cm) from the location of the front end 28. The distance is selected by the depth of focus of the scanning device. Nevertheless, there is a maximum possible distance depending on the width of the bars that make up the cord. Width 0
. For a 0075 inch (0.2 mm) bar, the maximum exposure depth is 3 inches (
7. cm). For a wide bar 0.04 inches (1 mm) wide, the maximum depth of exposure is 10 inches (25 cm). For a 0.01 inch (0.25 mm) wide bar, the maximum depth of exposure is 4 inches (10 cm). An operator holds the device and moves it along a coded code or bar code, detects reflected light from the bar, and converts it into an electric signal. A suitably amplified signal is taken from the scanning device via cable 38 and electronics for signal decoding (not shown)
Transported to The cable also supplies the power to operate the scanning device. Alternatively, the battery may be housed in the handle and the decryption electronics may be provided on the substrate 40 in the handle. The coherent laser beam is generated by a laser diode provided at one end of barrel 44. The optical device 46 converts the scattered beam generated from the laser diode into a parallel beam. These optical devices may be of the type typically used in microscope objective lens systems or digital audio disc devices. When a microscope objective lens system is used, the objective is reversed in that the end closest to the diode is the end facing the specimen in the microscope. A telescopic optic 48 formed by two lenses 50 and 52 having a long focal length and a short focal length, respectively, reduces the beam from the collimating optics 46. The reduced beam is transmitted to the condenser lens 32.
Focuses on a point in front of beam port 28. Of course, the depth of illumination or depth of focus of the optical device takes into account reading the code over the entire distance as described above. [0012] Laser diodes generate coherent light in the infrared (typically 815 nm). Diode 42 is included in the assembly with a photodetector that works with the power control circuit to keep the intensity of the output beam substantially constant.
Suitable diodes are available from Mitsubishi Electronics America, Inc., Semiconductor Division, Sunnyvale, California, USA. Available from The power control circuits and other circuits used with the laser diode are specified in a specification issued by the company. Since the laser beam is substantially invisible, the visible light is marked (tracked).
Means for irradiating the code with the application beam. These tracking beam irradiation means 54 include a small high-intensity incandescent lamp 56. Light emitting diodes may be used. The optics associated with the lamp 56 in the tracking beam illuminating means 54 focus the tracking beam on the code in front of the beam opening. These optical devices have an opening 58, a lens 60, a spectral beam splitter 62, a laser beam splitter 74, and the condenser lens 32. Spectral beam splitter 62
Has a thin film coating that reflects the visible tracking beam to the laser beam splitter 74 below. The tracking beam then coincides coaxially with the laser beam, and both beams pass through the condenser lens 32 and the beam port 30. Of course, the laser beam passes directly through the laser beam splitter 74. A photodetector 66 (appropriately a photodiode or phototransistor, as appropriate) enters at the beam port and detects reflected light from the coded code focused by the collection lens 32 for the detector 66. , Which are located off the beam path. The detector is preferably located behind the upper surface of upper housing 14 to protect against ambient light from overhead illumination sources (typically fluorescent lights). However, the detector may be provided at the bottom of the upper housing 14. At that time, a spectral beam splitter that reflects the reflected laser beam to the detector soil is required. As long as the polarized light reflected by the glossy finished surface on the bar code is reflected, the reflected light reflected like a mirror has the same polarization (eg, linearly polarized light) as the incident laser beam. Have. The light reflected and dispersed from the barcode has half p-polarized light and half s-polarized light. The laser beam splitter reflects only the incoming s-polarized light from the barcode code. This s-polarized light is then transmitted through a spectral beam splitter 62 to a detector 66. Thus, noise in the output signal from the detector caused by reflections on glossy surfaces and other mirrors is substantially eliminated. Instead of the polarizing beam splitter 74, a normal beam splitter may be used to pass only s-polarized light. The laser diode 42 is oriented such that its output beam has a major axis perpendicular to the plane of illumination. The beam splitter is substantially elliptical. The beam diverges at about 13 ° (6.5 ° on both sides of the vertical axis) and 38 (19 ° on both sides of the horizontal axis). The first lens of the collimating beam forming device 46 is spaced from the laser diode and substantially focuses the entire beam (38 ° total) emitted from the laser diode. The laser beam generating means 20 and the tracking beam generating means 54 are mutually connected with the beam splitters 62 and 74, and other analog circuits (power control circuits) and lamps for operating and controlling the tone generator 78 and the laser diode 42. It is provided on a printed circuit board containing other analog circuits that excite 56. Circuit elements (resistors, capacitors, transistors and integrated circuit chips) are provided on the printed circuit board 68, but are not shown for simplicity. The substrate 68 is provided on the bottom of the substantially flat upper housing 14 as shown in FIG. The substrate is positioned by one of the mountings 30 supporting the condenser lens 32. The substrate is secured in place by clips or other means (not shown). The barrel 44 is attached to the substrate 68 by a rear bracket 82. Front bracket 80 also holds laser beam splitter 74. The optical device 54 and the lamp 56 are connected to the annular front bracket 8.
6 and mounted in a barrel 84 contained in the rear bracket 82. These brackets are attached to barrel 44. Also, the front bracket 8
6 supports a spectral beam splitter 62. Whole single assembly 20
Is inserted into the upper housing portion 14 and locked. The bracket is mounted in a resilient material, such as rubber, which substantially reduces damage to the active elements of the scanning device even if the gun of the scanning device is dropped. The trigger switch 90 turns on the diode 42 and turns on the tracking beam lamp 56. When the switch is closed, the beam is on for a period of time. Even when the switch is opened, the beam remains fully on for a period of time. While the beam is on, the operator scans the beam across the coded code. The tracking beam minimizes losing the coded code, even in brightly lit locations. Thus, the coded code can be detected with a high probability. The operation of the laser and tracking beam emitting means will be more apparent from FIG. FIG. 4 includes a ray diagram and shows the lens in more detail. A collimated beam forming optic typically has three plano-convex lenses with a magnification of about 20 times. The aperture or stop member 90 forms a collimated beam so that it is suitably 6 mm along the main or vertical axis. The telescopic optics section 48 has a lens 50 to form a beam focus near its lens 52. The focal length of lens 50 is suitably 27 mm and the focal length of lens 52 is about 4 mm
It is. This reduces the size of the beam in the vertical direction from 6 mm to about 1 mm. Condenser lens 32 suitably has an f-number (f 大 き い) greater than 50 in the vertical or longitudinal direction to the output laser beam. The condenser lens 32 and aperture stop member 92 in front of the detector 66 provide a constant illumination across the depth of focus of the scanning device in front of the beam port 28 (FIG. 1) and a constant illumination from the detector. Generate an output signal. This signal is decoded and a corresponding display is provided on the display board. FIGS. 5 and 6 show a condensing lens 32 which provides a constant illumination to the detector 66 by the reflected light of the laser beam from the coded code over a long irradiation depth.
, Aperture 92 and detector 66 cooperate. A constant illumination is provided by maintaining a constant collection angle for the light that is reflected and dispersed by the coded code. This constant light collection angle ensures that the detector signal is within a certain variation range over the depth of focus (illuminated) S of the optical device. FIG. 5 shows a configuration in which a portion rotated by 90 ° is removed in the path of the reflected light from the beam splitters 62 and 74 to the detector 66. Condensing lens is diameter D
And the detector aperture 92 has a diameter d. Distance from the condenser lens to the detector is S _1. The working surface of the light detector 66 is substantially aligned with the end of the opening 92. Therefore, the distance S ₁ is substantially not only the distance to the detector 66 but also
The distance to the opening 92. Distance from the condenser lens 32 to the maximum the irradiated depth of the point A is S _2. The minimum irradiation depth is the point B that comes into contact with the condenser lens 32. If the collection angles (θ _A and θ _B ) are equal, the amount of light collected from point A is the same as the amount of light collected from point B. The necessary condition of this condition is that θ _A and θ _B are small, that is, smaller than 1 radian, so that θ _A (〜D / S ₂ ) = θ _B (〜d / S ₁ ) (1) That is, D / S ₂ = D / S ₁ , d / D = S ₁ / S ₂ (2) Note that point B does not cause substantial refraction of light at point B since it is in contact with lens 32. The auxiliary variables S ₁ and S ₂ are the formulas of a thin lens 1 / f = 1 / S ₁ + 1 / S ₂ (3) where f is the focal length of the condenser lens 32. S ₂ is the maximum depth of focus, for example, from the beam port 28. 10 inches (25.4 cm). f is the focal length of the lens, determined by the position of the optimal surface for reading the dense (narrow bar) coded code. The relationship for d / D can be modified to: D / D = S ₁ / S ₂ = 1 / S ₂ [1 / f−1 / S ₂ ] = 1 / S ₂ [(S ₂ −f) / fS ₂ ] (4) or d / D = as _{[S 2 / f-1]} (5) an example, f is 50 mm, considering the case S2 is 250 mm, is as follows. D / D = [S ₂ / f−1] = 250 / 50−1 = [5-1] = 4 (6) In this case, the distance between the aperture 92 and the condenser lens 32 is as follows: It is as follows. 1 / S ₁ = [1 / f-1 / S ₂ ] = [S ₂ −f] / fS ₂ (7) = [250-50] / 50 × 250 = [2/125] (8) At this time, it is equal to S162.5 mm. As shown in FIG. 6, opening 92 need not be as close to detector 66 as in FIG. The light collection angles θ _A and θ _B are equal to each other. The optical means shown in FIGS. 5 and 6, (a) if the opening 92 of the detector is positioned so as not to limit the amount of light collected from point A, to (b) θ _A is theta _B If the aperture 92 limits the light collected from point B to be equal, and (c) a light-collecting area (photosensitive area) that is large enough to collect all light passing through the aperture 92 from point B In the case where the detector 66 has, it can be seen that the light reflected from the points A and B compensates for a certain light collecting effect. [0028] From the description of the according to the present invention, an improved compact code key member is configured to integrate a single structure
It will be appreciated that a light detection device is provided. This device has excellent impact resistance
You. The above embodiments are merely illustrative, and modifications and variations of the devices described herein are within the scope of the invention.

[Brief description of the drawings]   FIG.   FIG. 2 is a partial cross-sectional view showing a barcode scanning gun embodying the present invention.   FIG. 2   FIG. 2 is an end view showing a front end of the scanning gun shown in FIG. 1.   FIG. 3   FIG. 2 is an end view showing a rear end of the scanning gun shown in FIG. 1.   FIG. 4   FIG. 2 is a light ray diagram for explaining the operation of the optical system and the electronic elements of the scanning gun shown in FIG. 1.   FIG. 5   FIG. 4 is a diagram illustrating an operation of an optical device that collects light reflected from a coded code.   FIG. 6   FIG. 6 is a ray diagram similar to FIG. 5, but showing a slightly different aspect.   [Explanation of symbols]   In these drawings: 10: Barcode scanning gun; 12: Housing 16: handle portion; 20: single structure 32: condenser lens 42: laser diode; 44: barrel 80, 82: bracket (support) 90, 92: aperture; 62, 74: beam splitter 68: Printed circuit board

Claims (1)

Claims: 1. A housing having a port, wherein a light beam for irradiating a coded code comprising a relatively large reflection area and a small reflection area is emitted from the housing through the port. the port light rays reflected from said coded sign
To that passing into the housing through a laser diode and an optical system for forming an optical line, and a photodetector for receiving light rays that have been reflected light, means for supporting the photodetector in the housing And a printed circuit board having a circuit for connecting to the diode and the photodetector, wherein the laser diode and the optical system are assembled in a housing in a relation supported on the printed circuit board to form a single structure. A coded code detection device constituting a part. 2. A code detecting apparatus according to claim 1, wherein said photodetector is assembled together with said laser diode , said optical system and said printed circuit board in a single structure. Code detection device. 3. The coded code detecting apparatus according to claim 1, further comprising a barrel in which said laser diode and said optical device are disposed, wherein said barrel is provided between said printed circuit board and said barrel. And a support for assembling the barrel, the laser diode, and the optical system into a single structure.